U.S. patent application number 12/598964 was filed with the patent office on 2010-09-30 for electromechanical brake system with a failsafe energy supply and method for failsafe energy supply in an electromechanical brake system for vehicles.
Invention is credited to Jorgen Holzwarth.
Application Number | 20100243388 12/598964 |
Document ID | / |
Family ID | 39677329 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100243388 |
Kind Code |
A1 |
Holzwarth; Jorgen |
September 30, 2010 |
ELECTROMECHANICAL BRAKE SYSTEM WITH A FAILSAFE ENERGY SUPPLY AND
METHOD FOR FAILSAFE ENERGY SUPPLY IN AN ELECTROMECHANICAL BRAKE
SYSTEM FOR VEHICLES
Abstract
An electromechanical brake system and an associated method with
a failsafe energy supply, have a first to fourth brake module with
at least one control unit and brake actuation unit. In order to
supply the modules with electrical energy, the control unit and the
brake actuation unit are each connected to at least one main energy
supply unit via independently fed lines. In order to supply
additional electrical energy to the modules, a first emergency
energy supply unit is connected to the control unit and brake
actuation unit of the first and fourth brake module and a second
emergency energy supply unit is connected to those of the second
and third brake module, respectively via additional independently
fed lines, wherein the selection of the energy supply unit is made
via switches actuated at least partially separately from one
another via at least one central control system.
Inventors: |
Holzwarth; Jorgen;
(Regensburg, DE) |
Correspondence
Address: |
King & Spalding LLP
401 Congress Avenue, Suite 3200
Austin
TX
78701
US
|
Family ID: |
39677329 |
Appl. No.: |
12/598964 |
Filed: |
April 29, 2008 |
PCT Filed: |
April 29, 2008 |
PCT NO: |
PCT/EP2008/055276 |
371 Date: |
May 21, 2010 |
Current U.S.
Class: |
188/158 ;
701/70 |
Current CPC
Class: |
B60T 8/885 20130101;
B60T 2270/414 20130101; B60T 2270/404 20130101; B60T 13/741
20130101; B60T 2270/413 20130101 |
Class at
Publication: |
188/158 ;
701/70 |
International
Class: |
B60T 13/74 20060101
B60T013/74; G06F 19/00 20060101 G06F019/00; F16D 65/34 20060101
F16D065/34 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2007 |
DE |
10 2007 021 286.2 |
Claims
1. An electromechanical brake system for vehicles with a failsafe
energy distribution comprising a first to fourth brake module
associated respectively with a wheel of the vehicle, each brake
module comprising at least one control device and a brake actuator
unit, wherein the control device and the brake actuator unit of a
brake module being connected respectively by way of separately fed
energy supply lines to at least one main energy supply unit to
supply the brake modules with electrical energy, wherein to supply
the brake modules additionally with electrical energy a first
emergency energy supply unit is connected to the control device and
to the brake actuator unit of the first and fourth brake module and
a second emergency energy supply is connected to the control device
and to the brake actuator unit of the second and third brake module
by way of respectively additional separately fed energy supply
lines, the selection of the energy supply units provided to supply
energy to the brake module being made by way of switching means,
which can be activated at least partially separately from one
another by way of at least one central control system.
2. The electromechanical brake system according to claim 1, wherein
to control the distribution of the electrical energy to the
respective control device and the respective brake actuator unit,
at least a first and second voter unit are provided.
3. The electromechanical brake system according to claim 1, wherein
first to eighth switching means are provided to switch through the
energy supply lines and additional first to eighth switching means
are provided to switch through the additional energy supply lines,
it being possible to switch these separately from one another.
4. The electromechanical brake system according to claim 3, wherein
the first voter unit is provided to control the first to eighth
switching means and the second voter unit is provided to control
the additional first to eighth switching means.
5. The electromechanical brake system according to claim 1, wherein
a switching means is formed by a controllable switching element or
a series circuit of two controllable switching elements or a series
circuit of one controllable switching element and a diode
element.
6. The electromechanical brake system according to claim 1, wherein
in the state without current or voltage the switching means have a
predetermined switching state, which is selected variously as a
function of the respectively present switching structure.
7. The electromechanical brake system according to claim 1, wherein
the first brake module is associated with the right front wheel,
the second brake module with the left front wheel, the third brake
module with the right rear wheel and the fourth brake module with
the left rear wheel.
8. The electromechanical brake system according to claim 1, wherein
the association of the energy supply units with the brake modules
is selected such that the brake circuits are allocated diagonally,
by side, by axis or by wheel.
9. The electromechanical brake system according to claim 1, wherein
the energy supply to the first or second voter unit can be
disconnected by way of further switching means, it being possible
for the switching means to be controlled by way of at least one
control unit provided in the central control system.
10. The electromechanical brake system according to claim 9,
wherein the at least one control unit is set up to evaluate the
voltages and/or currents present at the brake actuator units, with
the energy supply to the first or second voter unit being
disconnected by way of the further switching means as a function of
the result of the evaluation.
11. A method for failsafe energy distribution in an
electromechanical brake system for vehicles comprising a first to
fourth brake module associated respectively with a wheel of the
vehicle, each brake module comprising at least one control device
and a brake actuator unit, wherein the control device and the brake
actuator unit of a brake module are supplied with electrical energy
separately from one another under the control of at least one
central control system, the method comprising the steps of:
detecting the occurrence of a first and second system fault by way
of the at least one central control system and controlling the
energy distribution in the electromechanical brake system by way of
the at least one central control system such that after the
occurrence of a first and second system fault at least two brake
modules are still available to brake the vehicle and at least one
of the remaining brake modules affected by the first and/or second
system fault is disconnected.
12. The method according to claim 11, wherein the electrical energy
is supplied from at least one main energy supply unit to the brake
modules respectively by way of separately fed energy supply lines
and additional electrical energy is supplied to the control device
and to the brake actuator unit of the first and fourth brake module
by way of a first emergency energy supply unit and to the control
device and to the brake actuator unit of the second and third brake
module by way of a second emergency energy supply unit, being
supplied by way of respectively additional, separately fed energy
supply lines.
13. The method according to claim 12, wherein the energy supply
lines are switched through separately from one another by way of
first to eighth switching means and the additional energy supply
lines are switched through separately from one another by way of
additional first to eighth switching means.
14. The method according to claim 11, wherein the electrical energy
is distributed to the wheels of the vehicle by side, by axle or by
wheel.
15. The method according to claim 13, wherein in the state without
current or voltage the switching means are controlled to a
predetermined switching state, which is selected variously as a
function of the respectively present switching structure.
16. The electromechanical brake system according to claim 1,
wherein in the state without current or voltage the switching means
have a predetermined switching state, which is selected variously
as a function of the number of voter units provided.
17. An electromechanical brake system for vehicles with a failsafe
energy distribution comprising: a first to fourth brake module each
being associated with a wheel of the vehicle, wherein each brake
module comprising at least one control device and a brake actuator
unit, wherein the control device and the brake actuator unit of a
brake module being connected respectively by way of separately fed
first energy supply lines to at least one main energy supply unit
and the control device and to the brake actuator unit of the first
and fourth brake module are furthermore connected to a first
emergency energy supply unit and the control device and the brake
actuator unit of the second and third brake module are connected to
a second emergency energy supply, and a central control system
operable to control a plurality of switching means operable to
select the energy supply units provided to supply energy to the
brake module.
18. The electromechanical brake system according to claim 17,
wherein to control the distribution of the electrical energy to the
respective control device and the respective brake actuator unit,
at least a first and second voter unit are provided.
19. The electromechanical brake system according to claim 17,
wherein first to eighth switching means are provided to switch
through the energy supply lines and additional first to eighth
switching means are provided to switch through the additional
energy supply lines, it being possible to switch these separately
from one another.
20. The electromechanical brake system according to claim 19,
wherein the first voter unit is provided to control the first to
eighth switching means and the second voter unit is provided to
control the additional first to eighth switching means.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/EP2008/055276 filed Apr. 29,
2008, which designates the United States of America, and claims
priority to German Application No. 10 2007 021 286.2 filed May 7,
2007, the contents of which are hereby incorporated by reference in
their entirety.
TECHNICAL FIELD
[0002] The invention relates to an electromechanical brake system
with a failsafe energy supply and a method for failsafe energy
supply in an electromechanical brake system for vehicles.
BACKGROUND
[0003] Electromechanical brake systems, in particular for vehicles,
are known, wherein the hydraulic brake actuator units provided to
transmit the braking force to the brake disk connected to a wheel
are replaced by high-performance electromechanical brake actuator
units, which can be controlled and regulated electrically by a
central control system disposed in the vehicle. Such
electromechanical brake systems are also referred to as brake by
wire systems. Such a brake actuator unit can be configured as a
fully electronic, electro-hydraulic or electro-pneumatic unit.
[0004] The brake actuator unit is generally disposed together with
at least one control device in a brake module, which is associated
with a wheel of the vehicle. The brake actuator unit is activated
by way of the control device associated with the brake actuator
unit. The control device receives the control commands required to
activate the brake actuator unit from the at least one control
system disposed centrally in the vehicle, which generally activates
four brake modules associated with the respective wheels in a
common manner.
[0005] By actuating an actuation element provided in the vehicle,
for example a brake pedal, at least one electronic brake signal is
generated, which is transmitted to the central control system and
activation of the respective control device and thus the associated
brake actuator unit is effected as a function thereof.
[0006] One important criterion for the described electromechanical
brake system is the identification, elimination and control of
system faults occurring in the central control system and/or in the
brake modules and/or in the energy supply to the cited components,
which can threaten the availability of the electromechanical brake
system and thus the safety of the occupants of the vehicle.
[0007] Such electromechanical brake systems frequently have
auxiliary brake functions, by way of which actuation on controlled
stages (secondary braking) of individual undamaged brake actuator
units is still possible even after the occurrence of a fault. In
known brake systems in addition to actuation of the service brake
it is also possible to brake the vehicle using the parking brake,
in other words if one of the components affecting the service brake
fails, it is still possible to carry out secondary braking by way
of the actuation element of the parking brake.
[0008] Numerous designs for achieving "one fault tolerant"
electromechanical brake systems are already known from the prior
art. For example WO 99/26820 describes an electromechanical brake
system, the central control unit of which has three computer units,
the output signals of which are checked in respect of plausibility
by means of a voter unit. If the control signal of one of the
computer units deviates from the control signals generated by the
further computer units, it is identified as faulty by means of the
voter unit and the defective computer unit is excluded from further
signal processing. This should prevent activation of the brake
modules by means of defective control signals. If a second fault
now occurs in the form of the failure of the voter unit, further
reliable actuation of the brake system is no longer possible, in
other words a further second fault can result in the failure of the
entire electromechanical brake system.
[0009] With hydraulic brake systems in particular it is already
known that the brake circuits within the vehicle can be divided up
to increase fault tolerance. Similarly the brake circuit of the
electromechanical brake system can be broken down into at least two
brake circuits, in other words brake modules associated with at
least two different wheels respectively are combined to form one
functional unit and are activated in a common manner. For example
the brake modules associated with diagonally opposing wheels can
respectively form one functional unit. If one of said functional
units fails, it is possible to continue braking by way of the brake
actuator units of the functioning functional unit, in other words
secondary braking is ensured by actuating one of the two brake
circuits of the service brake.
[0010] To supply the individual control devices and brake actuator
units of the brake modules of the electromechanical brake system
with electrical energy, in particularly the necessary operating
voltage or current strength, these are connected respectively for
example by way of separate energy supply lines to a main energy
supply unit. In addition to the main energy supply unit provision
is made in known systems for at least one emergency energy supply
unit, which absorbs a failure of the main energy supply unit and in
the event of a fault the energy supply to at least the
safety-related elements of the electromechanical brake system is
taken over by the emergency energy supply unit.
[0011] By disconnecting the energy supply it is also possible to
disconnect a defective brake module within the electromechanical
brake system and the energy supply to the brake actuator unit or
the associated control device is also interrupted. The brake module
which has been switched to be without current or voltage then opens
automatically. In particular if a second fault occurs, incorrect
actuation of a brake module may take place, with the result that an
undesirable braking force is generated. In this instance controlled
opening of the service brake is no longer possible by way of the
associated control device, in other words the service brake brakes
unexpectedly or locks, thereby endangering the drive stability of
the vehicle. Specific disconnection of the energy supply allows
such faults to be eliminated even if a first and second system
fault for example occur within the control device associated with
the individual wheel. The remaining functioning brake modules are
advantageously available for secondary braking and therefore
controlled slowing of the vehicle.
[0012] With conventional electromechanical brake systems two
independent energy supply lines respectively are provided for each
brake module to supply the brake actuator unit and the control
device. Two independent switching paths are therefore available to
disconnect the energy supply to one brake module in each instance.
For the entire electromechanical brake system therefore eight power
supply lines have to be monitored by means of for example eight
voter units to achieve a "two fault tolerance", in other words one
voter unit has to be provided for each supply line. This involves a
high control and/or component outlay.
SUMMARY
[0013] According to various embodiments, an electromechanical brake
system with a failsafe energy supply and an associated method for
failsafe energy distribution in an electromechanical brake system
can be specified, which continues to ensure an energy supply to at
least two functioning brake modules after the occurrence of both a
first and a second system fault. The disconnection of brake modules
braking in an undesirable manner due to the occurring system faults
is also ensured by isolating their energy supply.
[0014] According to an embodiment, an electromechanical brake
system for vehicles with a failsafe energy distribution may
comprise a first to fourth brake module associated respectively
with a wheel of the vehicle, each comprising at least one control
device and a brake actuator unit, with the control device and the
brake actuator unit of a brake module being connected respectively
by way of separately fed energy supply lines to at least one main
energy supply unit to supply the brake modules with electrical
energy, wherein, to supply the brake modules additionally with
electrical energy, a first emergency energy supply unit is
connected to the control device and to the brake actuator unit of
the first and fourth brake module and a second emergency energy
supply is connected to the control device and to the brake actuator
unit of the second and third brake module by way of respectively
additional separately fed energy supply lines, the selection of the
energy supply units provided to supply energy to the brake module
being made by way of switching means, which can be activated at
least partially separately from one another by way of at least one
central control system.
[0015] According to a further embodiment, to control the
distribution of the electrical energy to the respective control
device and the respective brake actuator unit, at least a first and
second voter unit can be provided. According to a further
embodiment, first to eighth switching means can be provided to
switch through the energy supply lines and additional first to
eighth switching means are provided to switch through the
additional energy supply lines, it being possible to switch these
separately from one another. According to a further embodiment, the
first voter unit may be provided to control the first to eighth
switching means and the second voter unit is provided to control
the additional first to eighth switching means. According to a
further embodiment, a switching means can be formed by a
controllable switching element or a series circuit of two
controllable switching elements or a series circuit of one
controllable switching element and a diode element. According to a
further embodiment, in the state without current or voltage the
switching means may have a predetermined switching state, which is
selected variously as a function of the respectively present
switching structure, in particular the number of voter units
provided. According to a further embodiment, the first brake module
can be associated with the right front wheel, the second brake
module with the left front wheel, the third brake module with the
right rear wheel and the fourth brake module with the left rear
wheel. According to a further embodiment, the association of the
energy supply units with the brake modules can be selected such
that the brake circuits are allocated diagonally, by side, by axis
or by wheel. According to a further embodiment, the energy supply
to the first or second voter unit can be disconnected by way of
further switching means, it being possible for the switching means
to be controlled by way of at least one control unit provided in
the central control system. According to a further embodiment, the
at least one control unit can be set up to evaluate the voltages
and/or currents present at the brake actuator units, with the
energy supply to the first or second voter unit being disconnected
by way of the further switching means as a function of the result
of the evaluation.
[0016] According to another embodiment, a method for failsafe
energy distribution in an electromechanical brake system for
vehicles comprising a first to fourth brake module associated
respectively with a wheel of the vehicle, each comprising at least
one control device and a brake actuator unit, wherein the control
device and the brake actuator unit of a brake module are supplied
with electrical energy separately from one another under the
control of at least one central control system, may comprise the
steps of: detecting the occurrence of a first and second system
fault by way of the at least one central control system and
controlling the energy distribution in the electromechanical brake
system by way of the at least one central control system such that
after the occurrence of a first and second system fault at least
two brake modules are still available to brake the vehicle and at
least one of the remaining brake modules affected by the first
and/or second system fault is disconnected.
[0017] According to a further embodiment, the electrical energy can
be supplied from at least one main energy supply unit to the brake
modules respectively by way of separately fed energy supply lines
and additional electrical energy is supplied to the control device
and to the brake actuator unit of the first and fourth brake module
by way of a first emergency energy supply unit and to the control
device and to the brake actuator unit of the second and third brake
module by way of a second emergency energy supply unit, being
supplied by way of respectively additional, separately fed energy
supply lines. According to a further embodiment, the energy supply
lines can be switched through separately from one another by way of
first to eighth switching means and the additional energy supply
lines are switched through separately from one another by way of
additional first to eighth switching means. According to a further
embodiment, the electrical energy can be distributed to the wheels
of the vehicle by side, by axle or by wheel. According to a further
embodiment, in the state without current or voltage the switching
means can be controlled to a predetermined switching state, which
is selected variously as a function of the respectively present
switching structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention is described in more detail below based on an
exemplary embodiment with reference to figures, in which:
[0019] FIG. 1 shows a schematic block circuit diagram of an example
of an electromechanical brake system integrated in a vehicle,
[0020] FIG. 2 shows an example of a circuit structure with two
voter units provided to supply energy to the electromechanical
brake system,
[0021] FIG. 3 shows an example of a circuit structure with three
voter units provided to supply energy to the electromechanical
brake system,
[0022] FIG. 4 shows an example of a circuit structure with four
voter units provided to supply energy to the electromechanical
brake system, and
[0023] FIG. 5 shows an example of a segment of the switching
structure not shown in FIGS. 2 and 3 for detecting the voltage
and/or currents present at the brake modules.
DETAILED DESCRIPTION
[0024] According to various embodiments, to supply the brake
modules additionally with electrical energy a first emergency
energy supply unit is connected to the control device and to the
brake actuator unit of the first and fourth brake modules and a
second emergency energy supply is connected to the control device
and to the brake actuator unit of the second and third brake
modules by way of respectively additional, separately fed, energy
supply lines, the selection of the energy supply units provided to
supply energy to the brake modules being made by way of switching
means, which can be activated at least partially separately from
one another by way of at least one central control system. The
advantageous association of two brake modules respectively with an
emergency energy supply unit on the one hand and the provision of
centrally controllable switching means on the other hand mean that
the switching structure according to various embodiments allows
safe opening of a brake module that is braking in an undesirable
manner by disconnecting its electrical energy supply even after the
occurrence of a second fault (2 fault tolerance). To this end it is
sufficient to supply no further electrical energy at least to the
brake actuator unit or the control device of the defective brake
module, in other words to switch the brake module to be without
current or voltage, with the result that the brake actuator unit is
automatically opened. Also with the switching structure according
to various embodiments, at least two brake actuator modules are
still advantageously available for example for secondary braking
even after the occurrence of two faults in the energy supply to the
electromechanical brake system.
[0025] Also at least a first and second voter unit is
advantageously provided to control the distribution of the
electrical energy to the respective control device and the
respective brake actuator unit, being provided to control the first
to eighth switching means provided to switch the energy supply
lines through and the additional energy supply lines by way of
additional first to eighth switching means, which can be switched
separately from one another in each instance. The first voter unit
here is provided to control the first to eighth switching means and
the second voter unit is provided to control the additional first
to eighth switching means. A switching means can be formed for
example by a controllable switching element or a series circuit of
two controllable switching elements or a series circuit of one
controllable switching element and a diode element.
[0026] In the state without current or voltage the switching means
particularly advantageously have a predetermined switching state,
which can be selected variously as a function of the respectively
present switching structure, in particular the number of voter
units provided. This switching state advantageously takes on a
state that is safe for driving the vehicle if the controlling unit
fails. This switching state can either connect a brake module to a
specifically selected energy source or isolate said brake module
from a specifically selected energy source without activation, i.e.
by default so to speak, as a function of the switching
structure.
[0027] According to an embodiment, the association of the energy
supply units with the brake modules is selected such that the brake
circuits are allocated diagonally, by side, by axis or by
wheel.
[0028] In particular when two voter units are used, the energy
supply to the first or second voter unit can be disconnected by way
of further switching means, it being possible to control the
switching means by way of at least one control unit provided in the
central control system. To this end the at least one control unit
is set up to evaluate the voltages and/or current present at the
brake actuator units, with the energy supply to the first or second
voter unit being disconnected by way of the further switching means
as a function of the result of the evaluation.
[0029] According to the method for failsafe energy distribution in
an electromechanical brake system for vehicles the occurrence of a
first and second system fault is also detected particularly
advantageously by way of the at least one central control system
and the energy distribution in the electromechanical brake system
is controlled by way of the at least one central control system
such that after the occurrence of a first and second system fault
at least two brake modules are still available to brake the vehicle
and at least one of the remaining brake modules affected by the
first and/or second system fault is disconnected.
[0030] FIG. 1 shows a schematic block circuit diagram of an example
of an electromechanical brake system integrated in a vehicle F,
which is provided to brake at least one right and left front wheel
WFR, WFL and one right and left rear wheel WRR, WRL.
[0031] In the present exemplary embodiment the electromechanical
brake system has at least one central control system ECU and a
first to fourth brake module BM1 to BM4. By way of example the
first brake module BM1 is associated with the right front wheel
WFR, the second brake module BM2 with the left front wheel WFL, the
third brake module BM3 with the right rear wheel WRR and the fourth
brake module BM4 with the left rear wheel WRL.
[0032] The electromechanical brake system for example forms the
service brake system of the vehicle F, for the actuation of which
at least one actuation element BE is provided in the vehicle F. The
actuation element BE can be formed by a brake pedal for example,
which to this end is connected to the central control system ECU of
the electromechanical brake system. At least one further
electromechanical brake system, for example an electronic parking
brake system (not shown in the figures) can also be provided in the
vehicle F, for the actuation of which further actuation elements
and in some instances also an additional control arrangement can be
provided in the vehicle.
[0033] In the exemplary embodiment being considered the at least
one central control system ECU has at least one first, second and
third control unit C1, C2, C3 and at least two voter units IC1, IC2
(2 voter design), these being a first and second voter unit IC1,
IC2, with one of the voter units IC1, IC2 respectively being
connected to one of the control units C1, C2, C3, in other words
the first and second voter units IC1, IC2 are connected
individually to the first to third control units C1, C2, C3
respectively, among other things to monitor the fault-free
operation of these. The control units C1-C3 are configured as
microcontrollers in one preferred embodiment.
[0034] In the present embodiment the activation of the first to
fourth brake modules BM1-BM4 of the electromechanical brake system
is designed with threefold redundancy, in other words if one of the
first to third control units C1-C3 operates defectively, the
defective control unit is identified by at least one of the two
voter units IC1, IC2 and excluded from signal processing for
controlling the electromechanical brake system. To this end the at
least two voter units IC1, IC2 perform one or more appropriate test
functions, for example comparing the output signals of the first to
third control unit C1-C3.
[0035] In the present exemplary embodiment at least one first and
second voter unit IC1, IC2 are provided to increase the fault
tolerance of the electromechanical brake system, so that if one of
the voter units IC1, IC2 fails a functioning voter unit remains to
monitor the first to third control unit C1-C3. To further increase
fault tolerance, in an alternative embodiment according to FIG. 3
for example a first to third voter unit IC1, IC2, IC3 can be
provided or according to FIG. 4 a first to fourth voter unit IC1,
IC2, IC3, IC4 can be provided. This again improves the
susceptibility to error and the reliability of the
electromechanical brake system considerably. The voter units IC1,
IC2, IC3, IC4 can be configured here as hardware voter units or as
software voter units. With configuration as software voter units in
particular, they can be integrated in control units already
provided in the electromechanical brake system, for example the
first to third control units C1-C3.
[0036] The first to fourth brake modules BM1 to BM4 respectively
have a brake actuator unit BAE1 to BAE4 and a control device SG1 to
SG4. In particular a first brake actuator unit BAE1 and a first
control device SG1 are provided in the first brake module BM1, a
second brake actuator unit BAE2 and a second control device SG2 are
provided in the second brake module BM2, a third brake actuator
unit BAE3 and a third control device SG3 are provided in the third
brake module BM3 and a fourth brake actuator unit BAE4 and a fourth
control device SG4 are provided in the fourth brake module BM4,
with the first to fourth control device SG1 to SG4 being connected
respectively to the associated first to fourth brake actuator unit
BAE1 to BAE4.
[0037] The electromechanical brake system is connected to at least
one main energy supply unit HEV, for example the vehicle battery,
and at least one first and second emergency energy supply unit
NEV1, NEV2 to supply the first to fourth brake module BM1 to BM4 or
the first to fourth brake actuator unit BAE1 to BAE4 and the first
to fourth control device SG1 to SG4 with electrical energy. The
first and second emergency energy supply units NEV1, NEV2 can be
formed for example by additional battery units provided in the
vehicle F.
[0038] The above-mentioned energy supply units HEV, NEV1, NEV2 are
connected for example to the central control system ECU, which
regulates the distribution of electrical energy supplied by the
main energy supply unit HEV and the at least first and second
emergency energy supply units NEV1, NEV2 within the
electromechanical brake system.
[0039] To this end for example according to FIG. 2 the first to
fourth control device SG1-SG4 and the first to fourth brake
actuator unit BAE1-BAE4 are connected respectively to the main
energy supply unit HVE by way of separately fed first to eighth
energy supply lines VL11, VL12, VL21, VL22, VL31, VL32, VL41, VL42,
preferably by way of the central control system ECU. The first to
eighth energy supply lines VL11, VL12, VL21, VL22, VL31, VL32,
VL41, VL42 have first to eighth switching means SM11, SM12, SM21,
SM22, SM31, SM32, SM41, SM42, which can be switched by way of the
central control system ECU, in particular the first and second
voter unit IC1, IC2 disposed there.
[0040] To supply the first to fourth brake module BM1-BM4 or its
first to fourth control device SG1-SG4 and its first to fourth
brake actuator unit BAE1-BAE4 additionally with electrical energy,
the first emergency energy supply unit NVE1 for example is
connected to the first and fourth control device SG1, SG4 and to
the first and fourth brake actuator unit BAE1, BAE4 of the first
and fourth brake module BM1, BM4 and the second emergency energy
supply unit NVE2 is connected to the second and third control
device SG2, SG3 and to the second and third brake actuator unit
BAE2, BAE3 of the second and third brake module BM2, BM3 by way of
separately fed first to eighth additional energy supply lines
VL11', VL12', VL21', VL22', VL31', VL32', VL41', VL42', in other
words if the main energy supply unit HVE fails, an emergency supply
is ensured to at least two brake modules BM1-BM4 by way of the
first and/or second emergency energy supply unit NEV1, NEV2.
[0041] Advantageously two brake modules BM1-BM4 are associated
respectively with each emergency energy supply unit NEV1, NEV2
thereby allowing the cabling outlay and complexity to be
significantly reduced and meaning that it is not necessary to
connect every brake module BM1-BM4 to the first and second
emergency energy supply units NEV1, NEV 2 as a result.
[0042] The described switching structure predetermines for example
a diagonal brake circuit design, in other words the first and
fourth brake modules BM1, BM4, which are arranged diagonally
opposite one another in the vehicle F, are connected to the first
emergency energy supply unit NVE1 and the second and third brake
modules BM2, BM3, which are likewise arranged diagonally opposite
one another in the vehicle F, are connected to the second emergency
energy supply unit NVE2. The described switching structure is
selected by way of example. It is clear that numerous other brake
circuit allocations are possible, for example allocation by side,
by axle or by wheel.
[0043] The energy supply unit HVE, NVE1, NVE2 provided to supply
energy to the first to fourth brake modules BM1-BM4 is selected by
way of switching means SM11-SM42, SM11'-SM42', which can be
activated at least partially separately from one another by way of
the central control system ECU. In the exemplary embodiment
according to FIG. 2 for example 8 of the total of 16 switching
means SM11-SM42, SM11'-SM42' are activated by way of one of the two
voter units IC1, IC2. Increasing the number of voter units
according to FIGS. 3 and 4 increases the independence of the
switching paths available for energy supply purposes.
[0044] The energy supply lines VL11-VL42, VL11'-VL42' (switching or
supply paths) shown in the figures can also be formed by lines of a
bus system and/or further control devices provided in the vehicle F
(not shown in the figures).
[0045] With the switching structure shown in FIG. 2 the switching
means SM11-SM42, SM11'-SM42' are activated or switched by way of
the at least two voter units IC1, IC2, thus controlling the
distribution of the electrical energy supplied by the
above-mentioned energy supply units HEV, NEV1, NEV2. In this
process the two energy supply lines VL11-VL42, VL11'-VL42'
connecting a brake actuator unit BAE1-BAE4 or a control device
SG1-SG4 to the respective energy supply unit HVE, NVE1, NVE2 and
the switching means SM11-SM42, SM11'-SM42' provided to switch these
through are respectively controlled separately from one another by
one of the two voter units IC1, IC2, so that even if one of the
voter units IC1, IC2 fails, at least one operational supply path is
available for each brake actuator unit BAE1-BAE4 or for each
control unit SG1-SG4 and can be opened or closed by actuating the
associated switching means SM11-SM42, SM11'-SM42' by way of the
remaining voter units IC1, IC2.
[0046] In one preferred embodiment in the state without current or
voltage the switching means SM11'-SM42' associated with the
additional energy supply lines VL11'-VL42' have a predetermined
switching state, i.e. are configured as either open or closed. The
predetermined switching state is selected variously here as a
function of the respectively present switching structure, in
particular the number of voter units IC1-IC4 provided in the
central control system ECU. If for example a first and second voter
unit IC1, IC2 are provided, in the state without current or voltage
the switching means SM11'-SM42' are closed as standard while in the
case of an implementation having a first to third voter unit
IC1-IC3, they are opened as standard.
[0047] Therefore a total of 16 switchable supply paths (16 energy
supply lines VL11-VL42, VL11'-VL42' and 16 switching means
SM11-SM42, SM11'-SM42') are available to supply the electrical
energy to the first to fourth brake module BM1-BM4. Specifically
for example according to FIG. 2 the first brake actuator unit BAE1
is connected by way of first switching means SM11 and the first
energy supply line VL11 to the main energy supply unit HVE and by
way of additional first switching means SM11' and the first
additional energy supply line VL11' to the first emergency energy
supply unit NEV1. The first switching means SM11 are controlled by
means of the second voter unit IC2 and the additional first
switching means SM11' are controlled by means of the first voter
unit IC1.
[0048] The first control device SG1 is connected by way of second
switching means SM12 and the second energy supply line VL12 to the
main energy supply unit HVE and by way of additional second
switching means SM12' and the second additional energy supply line
VL12' to the first emergency energy supply unit NEV1, with the
second switching means SM12 being activated by means of the first
voter unit IC1 and the additional second switching means SM12' by
means of the second voter unit IC2.
[0049] Third switching means SM21 and a third energy supply line
VL21 are provided to connect the second brake actuator unit BAE2 to
the main energy supply unit HVE and additional third switching
means SM21' and an additional third energy supply line VL21' are
provided for connection to the second emergency energy supply unit
NEV2, it being possible for the third switching means SM21 to be
switched by means of the second voter unit IC2 and the additional
third switching means SM21' to be switched by means of the first
voter unit IC1.
[0050] The second control device SG2 is also connected by way of
fourth switching means SM22 and the fourth energy supply line VL22
to the main energy supply unit HVE and by way of additional fourth
switching means SM22' and a fourth additional energy supply line
VL22' to the second emergency energy supply unit NEV2, with the
fourth switching means SM22 being activated by means of the first
voter unit IC1 and the additional fourth switching means SM22' by
means of the second voter unit IC2.
[0051] The third brake actuator unit BAE3 is connected by way of
fifth switching means SM31 and the fifth energy supply line VL31 to
the main energy supply unit HVE and by way of additional fifth
switching means SM31' and a fifth additional energy supply line
VL31' to the second emergency energy supply unit NEV2. The fifth
switching means SM31 are controlled here by way of the second voter
unit IC2 and the additional fifth switching means SM31' by way of
the first voter unit IC1.
[0052] The third control device SG3 is connected by way of sixth
switching means SM32 and the sixth energy supply line VL32 to the
main energy supply unit HVE and by way of additional sixth
switching means SM32' and an additional sixth energy supply line
VL32' to the second emergency energy supply unit NEV2, with the
sixth switching means SM32 being activated by the first voter unit
IC1 and the additional sixth switching means SM32' by the second
voter unit IC2.
[0053] Finally the fourth brake actuator unit BAE4 is connected by
way of seventh switching means SM41 and the seventh energy supply
line VL41 to the main energy supply unit HVE and by way of
additional seventh switching means SM41' and an additional seventh
energy supply line VL41' to the first emergency energy supply unit
NEV1. The seventh switching means SM41 are controlled here by way
of the second voter unit IC2 and the additional seventh switching
means SM41' by way of the first voter unit IC1.
[0054] The fourth control device SG4 is also connected by way of
eighth switching means SM42 and the eighth energy supply line VL42
to the main energy supply unit HVE and by way of additional eighth
switching means SM42' and an additional eighth energy supply line
VL42' to the second emergency energy supply unit NEV2. The eighth
switching means SM42 are activated by way of the first voter unit
IC1 and the additional eighth switching means SM42' by way of the
second voter unit IC2.
[0055] In the exemplary embodiment shown in FIG. 2 with a first and
second voter unit IC1, IC2 the additional switching means
SM11'-SM42' are designed so that they are closed, if the first or
second voter unit IC1, IC2 fails, i.e. is in the state without
current. Also the switching means SM11, SM11', SM21, SM21', SM31,
SM31', SM41, SM41' provided to supply electrical energy to the
brake actuator units BAE1-BAE4 are formed respectively by two
switching elements connected in series, while the switching means
SM12, SM12', SM22, SM22', SM32, SM32', SM42, SM42' provided to
supply electrical energy to the control devices SG1-SG4
respectively have a switching element and diode element likewise
connected in series for example.
[0056] Normally, i.e. when there is no fault, the brake modules
BM1-BM4 are supplied with electrical energy by way of the main
energy supply unit HVE, i.e. the first to eighth switching means
SM11-SM42 are closed for the transmission of electrical energy by
way of the first to eighth energy supply line VL11-VL42 and the
additional first to eighth switching means SM11'-SM42' are open for
switching through the additional first to eighth energy supply
lines VL11'-VL42'.
[0057] In order in the event of a fault to be able to switch the
switching means SM11-SM42, SM11'-SM42' controlled by the first
and/or second voter unit IC1, IC2 to be without current, hereby
bringing about the opening or closing of the affected switching
means SM11-SM42, SM11'-SM42' as a function of the predetermined
switching state of the switching means SM11-SM42, SM11'-SM42', the
energy supply to the first or second voter unit IC1, IC2 can be
disconnected by way of further switching means SMC1, SMC2, being
for example controlled by way of at least one of the control units
C1, C2, C3. FIG. 5 shows a schematic block circuit diagram of an
example of a corresponding segment of the circuit structure.
[0058] The control units C1 and C2, which are preferably configured
as microcontrollers, generally have voltage regulator units, which
can be used to evaluate the voltages and/or currents present at the
brake actuator units BAE1-BAE4. The first control unit C1 is
connected by way of a first further switching means SMC1 and the
second control unit C2 by way of a second further switching means
SMC2 to the first or second voter unit IC1, IC2. If a malfunction
of one of the brake actuator units BAE1-BAE4 is detected for
example by at least one of the control units C1, C2, the affected
voter unit IC1, IC2 can be switched to be without current by
opening the switching means SMC1, SMC2 associated with the voter
unit IC1, IC2 to be disconnected, thereby switching the switching
means SM11-SM42, SM11'-SM42' associated with the disconnected voter
unit IC1, IC2 to the respectively predetermined switching state,
for example closing it according to FIG. 2. This produces at least
two further switching paths for disconnecting a defective brake
module BM1-BM4.
[0059] In contrast to the circuit arrangement shown in FIG. 2, in
FIG. 3 at least one first to third voter unit IC1, IC2, IC3 (3
voter design) is provided to control the switching means SM11-SM42,
SM11'-SM42'. Three voter units IC1, IC2, IC3 are now available to
control the energy supply by way of the 16 energy supply lines
VL11-VL42, VL11'-VL42', i.e. 4 of the 16 switching means SM11-SM42,
SM11'-SM42' are activated respectively by the first and second
voter unit IC1, IC2 and 8 of the 16 switching means SM11-SM42,
SM11'-SM42' are activated by the third voter unit IC3. In order to
be able to prevent undesirable braking of the electromechanical
brake system reliably even after the occurrence of a second fault
in the energy distribution, provision is made for the circuit
principle shown in FIG. 5, with the result that additional
switching paths are provided. If under the control of one or more
control units C1-C3 one of the voter units IC1-IC3 is isolated from
the energy supply by means of the further switching means SMC1,
SMC2, the associated switching means SM11-SM42, SM11'-SM42' are
open as standard, which in turn results in the disconnection of the
energy supply to individual brake modules BM1-BM4 and the resulting
triggering of the respective brake actuator unit BME1-BME4.
[0060] In a further particularly advantageous variant according to
FIG. 4 a first to fourth voter unit IC1, IC2, IC3, IC4 (4 voter
design) is provided to control the switching means SM11-SM42,
SM11'-SM42'. Here a voter unit IC1, IC2, IC3, IC4 is associated
respectively with one of the four energy supply lines VL11-VL42,
VL11'-VL42' or switching means SM11-SM42, SM11'-SM42' provided to
supply energy to a brake module BM1-BM4, in other words these can
be switched independently of one another. To prevent undesirable
braking of a brake module BM1-BM4, the energy supply at least to
one brake actuator unit BAE1-BAE4 and/or one control unit SG1-SG4
of the corresponding brake module BM1-BM4 should be interrupted.
The illustrated allocation of the switching means SM11-SM42,
SM11'-SM42' ensures a 2 fault tolerance, i.e. even if two of the
four voter units IC1-IC4 fail, secondary braking by way of the
remaining functioning brake modules BM1-BM4 is still possible.
[0061] If the third and fourth voter unit IC3, IC4 fails for
example during a braking operation, all the brake modules BM1-BM4,
the energy supply to which is controlled by means of the third and
fourth voter unit IC3, IC4, are switched to be without current or
voltage. In the present exemplary embodiment the energy supply to
the second brake actuator unit BAE2 (left front wheel WFL) and the
third brake actuator unit BAE3 (right rear wheel WFL) is
interrupted, i.e. the associated brakes open without current and
cannot cause undesirable braking. To achieve secondary braking, the
remaining functioning first and fourth brake module BM1, BM4 can be
actuated in stages for example. The first brake actuator unit BAE1
of the first brake module BM1 is supplied here with electrical
energy by way of the first energy supply line VL11 from the main
energy supply unit HVE and the first control unit SG1 is supplied
with electrical energy by way of the additional second energy
supply line VL21' from the first emergency energy supply unit NVE1.
Similarly the fourth brake actuator unit BAE4 of the fourth brake
module BM4 is supplied with electrical energy by way of the seventh
energy supply line VL41 from the main energy supply unit HVE and
the fourth control device SG4 is supplied with electrical energy by
way of the additional eighth energy supply line VL42' from the
first emergency energy supply unit NVE1.
[0062] The 2 fault tolerance of the described electromechanical
brake system is configured with absolute integration, in other
words if for example the main energy supply unit HVE and one of the
emergency energy supply units NVE1, NVE2 fail, secondary braking
can still be achieved by way of the remaining functioning emergency
energy supply NVE1, NVE2. Secondary braking is also ensured if just
one fault occurs at any time. Also adjusted braking force
distribution can also be provided for example under the control of
the central control system ECU for the still functioning brake
modules BM1-BM4, thereby ensuring safe drive stability.
[0063] The invention was described above using an exemplary
embodiment. It is evident that numerous changes and modifications
are possible without as a result departing from the inventive
concept underlying the invention.
* * * * *